<?php 
if (isset($_POST['sbumit'])):
?>



<?php
$u = $_POST['toi'];

if ($u=='mot'){
    var_dump($_POST);
    echo 'thanh cong ';}
    else { echo 'khong thanh cong';}
    
    ?>

<?php
else:
?>







<html>
    <body>
<form action="j.php" method="post">
    
    <input type="text" name="toi">
    <input type="submit" name="submit">
</form>
        
<?php
endif;
?>
        
    </body>

</html>